Leukemia is cancer of the body's blood-forming tissues, including the bone marrow and the lymphatic system.
Many types of leukemia exist. Some forms of leukemia are most common in children. Other forms of leukemia occur mostly in adults.
Leukemia usually starts in the white blood cells. Your white blood cells are potent infection fighters — they normally grow and divide in an orderly way, as your body needs them. But in people with leukemia, the bone marrow produces a large number of abnormal white blood cells, which don't function properly.
Treatment for leukemia can be complex — depending on the type of leukemia and other factors. But there are strategies and resources that can help to make your treatment successful.
Leukemia symptoms vary, depending on the type of leukemia. Common leukemia signs and symptoms include:
Fever or chills
Persistent fatigue, weakness
Losing weight without trying
Swollen lymph nodes, enlarged liver or spleen
Easy bleeding or bruising
Tiny red spots in your skin (petechiae)
Excessive sweating, especially at night
Bone pain or tenderness
Your body's lymphatic system is part of your immune system, which protects you against infection and disease. It includes your spleen, thymus, bone marrow, lymph nodes and lymph channels, as well as your tonsils and adenoids.
Lymphatic systemScientists don't understand the exact causes of leukemia. It seems to develop from a combination of genetic and environmental factors.
How leukemia forms
In general, leukemia occurs when some blood cells acquire mutations in their DNA — the instructions inside each cell that guide its action. The mutations cause the cell to grow and divide more rapidly and to continue living when normal cells would die. Over time, these abnormal cells can crowd out healthy blood cells, causing the signs and symptoms of leukemia.
How leukemia is classified
Doctors classify leukemia based on its speed of progression and the type of cells involved.
The first type of classification is by how fast the leukemia progresses:
Acute leukemia. In acute leukemia, the abnormal blood cells are immature blood cells (blasts). They can't carry out their normal work, and they multiply rapidly, so the disease worsens quickly. Acute leukemia requires aggressive, timely treatment.
Chronic leukemia. This type of leukemia involves more mature blood cells. These blood cells replicate or accumulate more slowly and can function normally for a period of time. Some forms of chronic leukemia initially produce no symptoms and can go unnoticed or undiagnosed for years.
The second type of classification is by type of white blood cell affected:
Lymphocytic leukemia. This type of leukemia affects the lymphoid cells or lymphocytes, which form lymphoid or lymphatic tissue. Lymphatic tissue makes up your immune system.
Myelogenous (MI-uh-loj-uh-nus) leukemia. This type of leukemia affects the myeloid cells. Myeloid cells give rise to red blood cells, white blood cells and platelet-producing cells.
Types of leukemia
The major types of leukemia are:
Acute lymphocytic leukemia (ALL). This is the most common type of leukemia in young children. ALL can also occur in adults.
Acute myelogenous leukemia (AML). AML is a common type of leukemia. It occurs in children and adults.
Chronic lymphocytic leukemia (CLL). With CLL, the most common adult leukemia, you may feel well for years without treatment. CLL is very rare in children.
Chronic myelogenous leukemia (CML). This type of leukemia mainly affects adults. A person with CML may have few or no symptoms for months or years before entering a phase in which the leukemia cells grow more quickly.
Other, rarer types of leukemia exist, including hairy cell leukemia.
· 9 years ago